1. Field
Embodiments of the present disclosure relate to a brake master cylinder.
2. Description of the Related Art
In general, a brake master cylinder for a vehicle is provided to be applied to a brake liquid pressure control apparatus for a vehicle, and is configured to transmit brake oil, which is introduced to the inside of the vehicle through a reservoir, to a wheel cylinder provided at each wheel by pressurizing the brake oil.
The brake master cylinder is provided with a device configured to turn on and off a brake lamp by sensing an operation of a piston according to a pedal force so that it is checked whether a vehicle is performing a braking operation. An example of the technology is disclosed in Korean Patent Registration No. 10-1085801, which relates to a master cylinder that turns on and off a brake lamp by using a hall sensor.
In the above document, the brake cylinder includes a ring-shaped magnet installed on a piston so as to move together with the piston according to a pedal force, and a hall sensor installed at a cylinder body, in which the piston is provided so as to reciprocate, at a position corresponding to a position of the magnet. The hall sensor detects the intensity of a magnetic force according to movement of the magnet installed on the piston, and transmit the detected intensity of the magnetic force to an electronic control unit (ECU) of the brake system, and the ECU regulates the on/off of a brake lamp that displays the status of braking operation of the vehicle based on a signal of the intensity.
Meanwhile, a piston may be rotated during an assembly or an operation of a brake master cylinder, and thus the positions of the hall sensor and the magnet may be mismatched, so that the hall sensor fails to properly detect the magnetic force of the magnet and the movement of the piston is not precisely detected. For this reason, a ring-shaped magnet is installed on the piston so that the movement of the piston is stably detected.
However, when the ring-shaped magnet is installed on the piston, a spring needs to be additionally installed to prevent the magnet from adhering to the piston, or an additional member needs to be processed to install the magnet on the piston, which complicates the installation structure.
In addition, since a ring-shaped magnet needs to be manufactured in consideration of rotation of the piston, a larger amount of magnet is required, which increase the manufacturing cost.